Electrical switch gear



Sept. 15, 1936. c. H. HILL ET AL ELECTRICAL SWITCH GEAR Filed July 31,1935 ISM/6 77 Their Attorney Patented Sept. 15, 1936 PATENT OFFICEELECTRICAL SlvVITCH GEAR Charles H. Hill and Kenneth T. Ashdown, DrexelHill, Pa., assignors to General Electric Company, a corporation of NewYork 7 Application July 31, 1935, Serial No. 33,985

Claims.

Our invention relates to electrical switchgear,

more particularly to means for interlocking the opening and closingoperations of two or more circuit breakers; In certain installations twoor more circuit breakers are arranged for alternatively controlling acircuit or circuits. Where circuit conditions require a definite andpredetermined order of operation, such as maintaining one breaker openwhen another breaker is closed, reliable interlocking means must beprovided. I The principal object of our invention is the provision ofimproved circuit breaker controlling and interlocking means for two ormore breakers which shall besirnple and compact in design and positiveand reliable in operation.

' Our invention will be more fully set forth in the followingdescription referring to the accompanying drawing, and the features ofnovelty which characterize our invention will be pointed out withparticularity in the claims annexed to and forming a part of thisspecification.

Referring to the drawing, Fig. 1 is an elevational view, partly insection, of switchgear of the drawouttype embodying our invention; Fig.2 is a simplified plan'view, looking downwardly, of part of theinterlocking mechanism of the switchgear shown by Fig. 1, and Fig. 3 isa perspective View or" the essential elements of the aforesaidinterlocking mechanism,

Referring to Fig. 1, the draw-out type switchgear illustrated byway ofexample, comprises a movable truck portion l mounted on wheels 2 and astationary portion or housing 3 in which stationary conductors orbusbars of the circuit, or circuits, to be controlled are mounted. Thetruck I is suitably formed of structural steel framework and supports acircuit breaker 4, anoil circuit breaker of conventional design beingshown in the present instance.

In operation, the circuit breaker i is electrically connected tocircuits in the stationary portion 3 through disengageable disconnectcontacts 5 of suitabledesign, the connection at ii being broken andthecircuit breaker isolated when the truck i is rolled. towards theleft, as viewed in Fig.1.

The operating means for the breaker l may comprise any suitablearrangement, a simple manual operating mechanism being illustratedcomprising a hand lever 5 pivoted to a stationary part of the truckframe at l, a connecting link 8, thrust transmitting toggle 9 andbreaker operating lever ID. The breaker i closed by straightening of thetoggle 9 and raising of the lever is.

Opening of the breaker may be eifected manually or by the usual tripcoil at H through the trip lever 52 and latch indicated at l3,permitting the link 8 to move towards the left with respect to handlever B byreason of the slot [4, thereby causing collapse of the toggle9.

For the purpose of preventing destructive arcing at the disconnectcontacts 5 by withdrawal of the truck while the breaker 4 is closed,suitable interlocking means is provided for tripping the breakerimmediately upon withdrawal of the truck. In the present instance a rodi5 is operatively connected tothe rackout mechanism at [6 so as toactuate the trip lever l2 through lever i1 and crank I 8 when the truckis withdrawn. The rackout mechanism comprises a worm gear mounted on thetruck and a coacting stationary rack, the worm gear being rotated by asocket wrench, or the like, exteriorly of the truck for moving the samewith respect to the stationary portion 3.

The rod l5, which is normally biased down- Wards as by gravity or springforce, is likewise connected through a compression spring I9 to apivoted latch 26 which is biased by the spring I9 so as to engage andhold, when in open circuit position, the end 2! of a bellcrank 22forming part of the toggle 9. The switchgear arrangement so fardescribed is illustrated and disclosed in more detail in Patent No.1,791,466 to H. G. French entitled Electric Switching Devices.

A plurality of truck-type units may be arranged in a row to form astation as indicated by Fig. 2 which illustrates two trucks l and Imovable with respect to the stationary circuit housing 3. In theinterest of clearness, the plan view, Fig. 2, omits the circuit breakersand operating mechanisms.

For the purpose of interlocking the operations of the breakers in thetruck units l and I, mechanical means are arranged between the operatingmechanism of each breaker and the tripping mechanism of the otherbreaker, causing in the present instance tripping of one breaker uponclosing of the other breaker and vice versa. The arrangement, whilepermitting both breakers to be in open circuit position, permits but onebreaker at a time to be in closed circuit position.

To this end a pair of independently rotatable shafts 23 and 24 aresuitably mounted in the housing 3 in bearings 25, the shaft 24 being inthe form of a sleeve mounted on and freely rotatable with respect to theshaft 23. Each shaft is provided with means for interlocking theoperating mechanism of one breaker and the tripping mechanism of theother breaker.

Referring more particularly to Fig. 3 wherein the breakers in the truckunits I and l are referred to as A and B, respectively, a bellcrank 26suitably mounted on the truckframe at 2! is connected through a link 28to the bellcrank 22 of the operating toggle. The bellcrank 26 islikewise connected to a rod 29 which may engage in abutting relation alug 30 secured to the shaft 24. As illustrated, the linkage arrangementconnected to breaker A is in the closed circuit position so that openingof the breaker and clockwise rotation of the bellcrank 26 merely movesthe rod 29 away from abutting engagement with the lug 3! withoutrotating the shaft 23.

The tripping mechanismof the breaker B comprises a rod IS on whichis'secured a'collar 3! arranged to coact with a bifurcated arm 32 of abellcrank 33 which is mounted on the truck frame at 34. V is connectedto a rod 35 which, as in the case of rod 29, is arranged to abut a lug30' secured to the shaft 24 in spaced angular relation with respect tolug 30. The relation between the lugs 38 and 30 is such that when thebreaker A is closed the rod 29 moves the lug 30 to such position thatthe lug 35 holds the rod 35' and bellcrank 33 in the position shownwherein the tripping rod I is in the tripping position. Accordingly,when the breaker A is in closed circuit position it is impossible toclose breaker B by reason of the inoperative condition of its trippingmechanism.

Assuming now that breaker A is opened, thereby causing movement of rod29 away from lug 30, the downward bias on rod l5 'resets the trippingmechanism of breaker B and causes clockwise rotation of lug 30' throughcrank 33.

Closing of thebreaker B may now be effected,

causing counterclockwise rotation of bellcrank 26 through the upwardmovement of rod 28 and movement of rod 29 towards 'theright to 'and 36'are mounted in spaced angular relation engage lug 36 which is secured toone end of the shaft 23. The shaft is accordingly rotated in acounterclockwise direction as is the lug 36 which is secured to theother end of the shaft As in the preceding instance, the lugs 36 videdwith a bifurcated arm 32' coacting with a collar 3! secured to the rodI5. Accordingly, counterclockwise rotation of shaft 23 in response toclosing of the breaker B causes clockwise rotat'i'onof bellcrank 33 andelevation of the rod I5 to the tripping or inoperative position.

It will, therefore, be noted that either breaker may be closed when theother breaker is open and that when both breakers are open the trippingmechanism of each is operative so that either one may be closed. Closingof both breakers at the same time, however, is positively precluded.

The interlocking arrangement disclosed is particularly advantageous ininstallations where a plurality of interchangeable switch units of thedraw-out type are required for the purpose of maintaining practicalcontinuity of operation. An individual truck unit may immediately beremoved from the station without affecting the in-.

The other arm of the bellcrank terlocking arrangement between the sameand another breaker and a similar unit may be moved without delay intooperative position without requiring any connections or adjustmentsbetween the truck unit and interlocking arrangement. Since each breakerof an interlocked pair ispractically identical with the other, anybreaker is interchangeable with any other in an installation using anumber of pairs of interlocked breakers of like capacity. It will beapparent, of course, that the interlocking arrangement above describedis not limited to twobreakers, and that, for example, breakers in'pairsmay be interlocked with respect to'other pairs.

It should be understood that our invention is not limited to specificdetails of construction and arrangement thereof herein illustrated, andthat changes and modifications may occur to one skilled in the artwithout departing from the spirit of our invention. 7 t 7 What we claimas new and desire to secure by Letters Patent of the United States is:7 1. In electrical switchgear including a plurality of circuit breakers,each breaker having a tripping mechanism and an operating mechanism,means for interlocking said breakers com prising a rotatable shaftoperatively related to the operating mechanism of one breaker and thetripping mechanism of another breaker respectively, and a secondrotatable shaft operatively related to the tripping mechanism of saidfirstnamed breaker and the operating mechanism of said other breakerrespectively.

2. In electrical switchgear including a plurality of circuit breakers,each breaker having a tripping mechanism and an operating mechanism,means for interlocking said circuit breakers comprising a memberoperatively related to the operating mechanism of one of said breakers,a sec-- ond member movable with said first member in fixed relationthereto and operatively related to the tripping mechanism of another ofsaid breakers, a third member operatively related to the trippingmechanism of said first-named breaker, and a fourth member movable withsaid third member in fixed relation thereto and operatively related'tothe operating mechanism of said other breaker.

3. In electrical switchgear including a'plurality of circuit breakers,each' breaker having a tripping mechanism and an operating 'mechanism,means for interlocking said circuit breakers comprising a rotatableshaft, interlock members secured to said shaft in fixed spaced relation,

,means operatively connected to the operating mechanism of one breakerand the tripping mechanism of another breaker arranged to engage inabutting relation said interlock members respectively, and a secondrotatable shaft having similar interlock members arranged to engage inabutting relation means operatively connected to the tripping mechanismof said first-named breaker and the operating mechanism of said otherbreaker respectively.

4. In truck type electrical switchgear including a plurality of movablecircuit breakers, each breaker having a tripping mechanism and anoperating mechanism, means for interlocking said circuit breakerscomprising a rotatable shaft having a pair of interlock member securedthereto in spaced angular relation, one of said members arranged toengage in abutting relation means operatively connected to the closingmechanism of. one of said breakers, the other of said members arrangedto engage in abutting relation means operatively connected to thetripping mechanism of another of said breakers, a second shaft arrangedin concentric relation and freely rotatable with respect to said firstshaft, a pair of interlock members secured in spaced angular relation tosaid second shaft, one of said lastnamed members arranged to engagein'abutting relation means operatively connected to the trippingmechanism of said first-named breaker and the other member arranged toengage in abutting relation means operatively connected to the closingmechanism of the other breaker.

5. In a station including a plurality of similar switchgear units 01'the draw-out type, each of said units having tripping means andactuating means, means for interlocking pairs of said units comprisingmeans mounted independently of said units and actuated thereby forcontrolling the tripping operation of one unit in accordance with theactuating operation of the other unit, each of said units being freelywithdrawable with respect to said interlocking means and interchangeablewith any other of said units.

CHARLES H. HILL. KENNETH T. ASHDOWN.

